Here's my $0.02 worth.

Remove shampoo, use bar soap period. I hate it when they leak all over.

Add swimmer's goggles for eye protection. They're small and lightweight. You have N95's but you may need some dust protection.

Double your number of garbage bags. If you need to go swimming it would be better to double bag your gear. You never know when the other two could come in handy for a multitude of things.

Consider adding a couple of aspirin tablets. With the stress of such an event you never know when you might need them to survive a heart attack. I'm over 50 too and I always carry a couple, just in case.

Overall I like your thinking. As a parallel, I am putting together something similar. But I have one advantage in that I have a car that will serve as a rescue ark. My office bag will be strictly used for getting out of the building and to my car.